It is common in video compression systems to require the movement of blocks of pixels to be estimated from one frame to the next. Rather than send the full frame of video information, only the deltas or movements, known as motion vectors, of the blocks of pixels need be sent. Video compression encoders perform such processing which results in a video bit rate greatly reduced form the original. Starting with the original initial frame, a video decoder can reconstruct the original frames by utilizing the motion vectors previously calculated for each of the blocks in the frame. A more in depth discussion of the motion estimation process can be found in "Image and Video Compression Standards, Algorithms and Architectures," by Vasudev Bhaskaran and Konstantinas Konstantinides.
Video compression encoders currently exist that can perform motion estimation on half pixels. However, they are generally large in size and are expensive. In line with the long term trend of manufacturing smaller and less expensive products, it would be very desirable to reduce the size, weight, cost and complexity of video compression encoders. In particular, the motion estimation portion of the video compression encoder would benefit a great deal if its size and cost were both reduced.